Method for production of tubular fibrous bodies



Oct. 15, 1968 w. L.. ULLMAN ETAL 3,406,231

METHOD FOR PRODUCTION OF1 TUBULAR FIBROUS BODIES Filed Jan. 20, 1964 5Sheets-Sheet 1 1N VEN TORS Oct. 15, 1968 w. L.. ULLMAN ETA'. 3,406,231

METHOD FOR PRODUCTION OF TUBULAR FIBROUS BODIES Filed aan. 2o, 1964 ssheets-sneer 2 A fil/ 14.2K

T TOR/VE ya Oct. 15, 1968 w. L. ULLMAN ETAL 3,406,231

METH-OD FOR PRODUCTION OF TUBULAR FIBROUS BODIES Filed Jan. 20, 1964 3Sheets-Sheet 5 g @www T TOP/VE K5? United States Patent O 3,406,231METHOD FOR PRODUCTION OF TUBULAR FIBROUS BODIES William L. Ullman,Cherry Hill, N J., and James C. Baxter, Minerva, Arthur J. Pearson,Granville, Robert E. Davis, Newark, and William B. Hullhorst, Rossford,Ohio, assignors to Owens-Corning Fiberglas Corporation, a corporation ofDelaware Filed Jan. 20, 1964, Ser. No. 339,007 5 Claims. (Cl. 264-145)This invention relates generally to tubular fibrous bodies `designedprimarily to Serve as independent ducts and thermal insulating coversbut also of utility for a variety of .other purposes. The inventionpertains particularly to ducts and pipe insulation of fibrous glass, andmethods for continuous fabrication of such products from a conventionalpack of fibrous glass created by gathering and felting the fibersattenuated from molten threads in a standard fibrous glass formingoperation.

The excellent performance of fibrous glass masses as thermal insulatingmedia is widely recognized. Not only highly resistant to heat transferfibrous glass also has exceptional strength, and is chemically inert, soable to withstand exposure to the corrosive action of moisture, mildew,insects and other destructive elements.

Previously, it has been the usual practice to build tubular members offibrous stock in stationary matrices or molds. This is not only a timeconsuming, costly procedure but also limits the length of the productsto the fixed dimensions of the molds. With such an arrangement there isalso the objectionable irregular production movement which necessitatesextra handling and intermittent storage.

Attempts to provide a more expeditious, continuous manufacturing systemproducing an endless tube which may be cut to any length desired havenot met with substantial success. Difficulties encountered have relatedto maintaining the operations coordinated, uniform feeding the fibrouscomponent, the establishment of a predetermined density, complexity andhigh cost of the processing equipment, and the lack of versatility ofsuch equipment.

A prime lpurpose of this invention is to provide an effective,continuous process and comparatively simple and inexpensive apparatusfor fabricating a constantly advancing, tubular body of bonded fibrousglass.

An important object of the invention also resides in the production of afibrous tube of uniform characteristics including desired density andinherent strength to withstand the stresses incurred in handling,transportation and installation.

Another object embraces a method and apparatus facilitating a selectiveVariation in the density and wall thickness of the tubular product. Y

An additional object resides in the provision of a process adapted toreceive and directly utilize a pack of fibrous glass as delivered from aconventional fibrous glass forming station.

A further object of the invention s the provision of means forimpregnating the tubular bodies with special additive materials.

Another object is a tubular product with selected areas of greaterdensity and strength and a method of creating such a product. Y

A supplemental purpose of the invention is to provide Vmeans forirregular shaping of the tubular bodies.

These and other objects and advantages of the invention are secured fromthe improved structure of the fibrous bodies and the particulararrangement and design of the apparatus provided.

The invention primarily involves apparatus for creating a stream ofglass fibers and gathering them in pack 3,406,231 Patented Oct. 15, 1968formation; coating the fibers in the stream with a bonding agent orimpregnating the formed pack therewith; depositing and conveying thepack upon a belt conveyor; then helically winding and compressing theendless pack upon a Smooth surfaced mandrel by means of a belt woundaround the mandrel; curing the binder of the fibrous stock, and movingthe wound tubular body of fibrous glass helically along the mandrel bymeans of the contacting, advancing turns of the belt.

Additional features and benefits of the invention will be apparent fromthe following description with reference to the drawings in which:

FIGURE 1 is a plan view of one form of apparatus embodying theinvention;

FIGURE 2 is a side elevation of the apparatus of FIGURE 1;

FIGURE 3 is a vertical cross section taken on line 3-3 of FIGURE 1;

FIGURE 4 is a view of the mandrel of the apparatus of FIGURES 1, 2 and 3shown on an enlarged scale;

FIGURE 5 is an enlarged cross sectional view of the mandrel with afibrous glass pack Wrapped therearound;

FIGURE 6 is an enlarged longitudinal and vertical section of the ironercomprising an element of the apparatus of FIGURES l and 2;

FIGURE 7 shows a portion of a particular form of a fibrous glass tubularbody, partly in section, which may be produced accordingly to theinvention with the apparatus illustrated in the preceding views;

FIGURE 8 is a longitudinal sectional view of an impregnating arrangementutilizing a portion of a modified design of mandrel;

FIGURE 9 is a like view of a different form of impregnating apparatus;

FIGURE 10 shows in side elevation, sawing devices cutting grooves in thefibrous tube as it moves along the end of the mandrel; and

FIGURE 11 is a sectional view taken on the line 11--11v of FIGURE 10.

Referring to the drawings in more detail, the apparatus for formingtubular bodies of fibrous glass shown in FIGURES 1 and 2 includes a mainplatform base 10. Upon one end of the platform is an upright post 11with a clamp 12 at its upper end forming a bore with the post forreceiving and holding the horizontally disposed mandrel 13.

The hollow mandrel may, for purposes of this description of theinvention, be six feet long and have a wall thickness of five sixteenthsof an inch and a diameter of six inches. A length of smooth-finishedstandard pipe plugged at both ends serves very satisfactorily. Themandrel preferably has a slight stock releasing taper from its supportedend. This reduction in diameter -may be one sixteenth of an inch foreach six inches of length.

Tightly fitted over the major portion of the mandrel and extending tothe outer end thereof is a Teflon sleeve 14, best seen in FIGURE 4. Thisprovides a non-adhesive surface. Sleeves or coatings of certainsilicones, graphite and other materials may also be used for thislubricating or non-sticking effect. Also, non-adhesion yto the mandrelmay be secured by delivering the fibrous pack on a backing of fibrousglass cloth, scrim, mat, paper or screening. Such material would inaddition provide an internal lining to the tubular product.

A section of the hollow mandrel v13 is perforated with a close array ofports 15 with matching ports in the Teflon sleeve 14. The ports are onesixteenth of an inch in diameter spaced one inch apart and extend over athirty inch area lengthwise of the mandrel.

Compressed air is delivered to the interior of the mandrel through inlet16 at the end of the mandrel mounted upon supporting post 11. Beforepassing out ports 15 this -air is customarilyl heated to a temperaturebetween 350 to 450 F. through contact with the resistant heating element.17 (FIGURE 4) positioned lengthwise within the mandrel. Electricalenergy is supplied the heating element through lead wires 18.'. l

A pack oflibrous glass preferably impregnatedwith a heat settable.binder is led at an angle and tangentially toward the stationarymandrel 13. This pack may be in a-width of sixteen inches, have ageneral thickness of one inch and an average density of three quartersof a pound per cubic foot.

While fibrous glass is the preferred material for the products of thisinvention, other mineral fibers, and' organic fibers, as well, in abroad range of sizes are reasonably suited for use in practicing thisinvention. Fairly exact control of the specifications of theglassftibersmay be exercised by selection of the orifice' diametersthrough Whichthe' molten glass is discharged in line stream form fromthe forehearth of the furnace. The ingredients of the basic glasscompositiony also may be chosen to give certain characteristics to thefibers created therefrom. The force andvolume of the gaseous blasts bywhich the rapidly-cooling molten threads are attenuated into fibers maybe varied to increase or decrease their elongating effect.

However, for purposes of this'invention and with consideration given thequalities desired in the tubular in'- sulatiug products, a fairly finefiber between fifteen and twenty-live hundred thousandths of an inch indiameter is preferred. A mass of such fibers has exceptional goodinsulating properties and is readily shaped and compacted. It should beunderstood that fibers in diameters as large as sixty hundredthousandths of an inch may be utilized with quite satisfactory results.

The pack 20 of fibrous glass incorporates a binder constituent,generally introduced in the forming hood, in a preferred proportion of,approximately ten to fourteen percent by weight in the event aconventional formulation of phenol formaldehyde and an additive ofvinsol (a resin ractionally derived distillant of southern pine) isemployed. This quantity is subject to alteration depending upon thestrength and porosity desired in the final product as well as upon thecharacter of the fibers. With special more tenacious binder compositionsthe percent may be reduced to as little as live and one half. The binderis usuallyof an organic base such as phenol, urea or melamineformaldehyde, silicone, epoxy, or alkyd resins and .applied in a liquidvehicle. However, powdered binders are used very successfully andinorganic and combinations of inorganic and organic are effective.

A hot air nozzle 21 is desirably positioned over the advancing pack tovolatilize the liquid vehicle of the binder and to initiate the curingof the binder.

The edge of the pack 20 is directed under the first turn around themandrel of a flat woven wire belt 23. The belt travels at an angle tothe mandrel corresponding to the angle of approach of the fibrous glasspack. The belt is driven between capstans 25 and 26, the latterproviding a positive drive due to a rubber coating thereon. The smoothsurface of capstan 25 allows a certain amount of slippage to maintainuniform tension.

For the particular embodiment of the apparatus here disclosed thecapstansl are eighteen inches in a diameter, have a vertical length oftwenty-four inches, and are spaced five feet apart. As may be seen inFIGURE 3, the capstans 25 and 26 are rotatively mounted respectively inbrackets 27 and 28. These brackets are carried on the sub-base 29pivotably set upon the platform 10. The desired belt angle across themandrel is obtained by turning the sub-base 29. The distance between thecapstans may be varied by rotating the threaded rod 30. The greater thebelt Width the more the capstans should be spaced apart.

The spindles 32 and 33 of the capstans 25 and 26 have bevel gears 35 and36 on their lower ends. From horizontal shaft38-V driving power istransferred to gears v35 and 36 through bevel gears 40 and 41 engagedtherewith. In turn, shaft 38 is rotated by a bevel gearing connectionwith the -vertical shaft ,43, the latter being actuated througlfbevelgearing by the primary shaft 45.(F1GURE 2). This shaft 45 carriesasprocket 46 for a chain drive from a motor .or an. intermediate speedreducer (not shown). t Y

With the pack of fibrousglass sixteen inches wide a twelve inchoverlapof each circumferential turn of the web over the ,immediately precedingturn,'the tubular body 47 thus formed has fourv layers of the pack. Thetension of the belt 23 is arranged to compress the helically wrappedfour layer, tubular body to a thickness of one inch. The body thus has awall thickness of one inch and an outside diameter of eight inches. Thethree loops of the belt enclosing and compressing the overlapping turnsof the pack not only form and compress the wrapped pack but also drivethe developed cylindrical body helically along the stationary mandrel.The wall thickness of the tubula-r product may be varied by the amountof overlapping of each successive turn of the pack and by 4the thicknessof the pack. The belt requires more lslack for the heavier-sectionedbodies. Then, too, because of the draftability of the fibrous pack thethickness may be varied through change of the relationship between thepack delivery speed and the belt winding rate. Y

Rapid curing of the binder of the fibrous glass is secured through theoutward discharge from the interior of the mandrel through the ports 15of air under less than a pound per square inch pressure and heated bycontact with heating element 17 between 350 and 450 F. These portsextend from apoint in front of the belt under the loops of the belt andsome distance beyond. Since the belt is not closely woven it does notblock the flow of air passing outwardly through the compressed wrappingof the pack. The radial fiow of the curing air is illustrated in FIGURE5.

While more difficult to control, an outer manifold directing heated airinwardly into the fibrous body would effect the needed curing. Alsosteam may be used in place of heated air. A dielectric heating field isanother alternate curing means. In case it is desired to cure only theinside of the tubular body a hot unperforated mandrel would be suitable.

The cylindrical bodyv 47 is dimensionally stabilized through the curingaction as it moves out of the compressing contact with the three loopsof the belt around the mandrel.

To smooth out irregularities in the surface of the cy- -lindrical bodyand to further advance, if necessary, the curing of lthe binder, anironer 48 is positioned in encircling relation to the mandrel adjacentto the belt station. As may be seen in FIGURE 6 the hollow ironer 48 hasa tapered entrance to a cylindrical bore with air ports 49 spacedtherearound. Compressed air entering through inlet 50 is heated by theresistance element 51 and discharged through ports 49. This air is at ahigher pressure than that issuing from ports 15 in the mandrel nctherefore is forced inwardly through the cylindrical As an alternate orsupplemental to the ironer 48, va belt sander may be placed in contactwith the surface of the advancing tubular body 47 of fibrous glass togrind olf irregular projections and to generally smooththe surfacethereof.

A finishing film 53 is guided around the tubular body 47 as shown inFIGURE l. This is preferably a thermoplastic which is first softened andthen shrunk by the effect of the heated curing air. It is thus broughttightly against the body. It may be applied with its turns inoverlapping or in edge abutting relation.

The belt S5 between capstans 57 and 58 is part of a second beltmechanism generally duplicating that including belt 23. The movement ofbelt 55, which may be turned only one or two times around the mandrelassists in pulling the tubular body along the mandrel and inconstricting the plastic finishing film 57.

The completed tubular insulating body 60 proceeds along the mandrel frombelt 55 over guide and supporting rollers 64 and 65 adjustably mountedon vertical stand 66. A diagrammatically illustrated reciprocating saw68 cuts the continuous tubular body 60 into units 70 of selected length.These move to inspection and packing stations from the conveyor 72comprising series of rollers 73 and 74 supported upon the stand 76.

In FIGURE 8 is shown the outer end of a modified form of mandrel 75.This has the outer sleeve 14 of Teflon or coating of other material suchas silicone or graphite to lubricate the movement of the cylindricalbody 60 of fibrous glass along the mandrel.

A circumferentially extending band of ports 79 through the wall of themandrel is confined within a chamberpbetween end members 77 and 85.Extending through end member 77 is piping 78 brought into the hollowmandrel from its supported end. This provides an inlet for supplyingimpregnating material for the cylindrical fibrous structure.

Should it be desired to produce a heavy bodied, hot temperatureserviceable product a slurry of mineral clay may be supplied throughinlet 7S and forced out ports 79 into the porous interior of the fibrousstructure 60 as it moves along the mandrel. This flow of slurry is aidedand excess removed by suction applied through outlet 82 of the annularcasing 88 positioned around the exterior of the moving cylindrical body60. A controlled residue of the slurry is thus drawn out of the fibrousstock through holes 90 on the inner surface of the casing 88.

Dry particles for other purposes may be air borne through thiscirculating arrangement and implanted in the fibrous stock. Powderedmineral salts thus introduced in the fibrous stock would increase thefire resistance thereof. Particles of activated carbon would improve theair purifying action of a cylindrical filter core made from this tubularproduct.

Should it be desired -to more heavily impregnate the outer portion ofthe fibrous cylinder with any such materials, this could be accomplishedby reversing the fiow and directing the material from the outsidethrough casing 88 into the fibrous body.

Shown in FIGURE 9 is another modified form of the invention some-whatsimilar to that of FIGURE 8. It involves an impregnating arrangementlocated in or adjacent to the binder curing area of the mandrel 84 inwhich the mandrel is quite continuously ported for the outward flow ofheated curing air. An annular member 88 is fitted tightly within themandrel. It has an axial opening 87 to allow some of the heated curingair to continue along the interior of the mandrel for subsequent radialdischarge. From an inlet pipe running from the supported end of themandrel, fluid material or air borne particles are brought into themember 86 and forced outwardly through mandrel ports 89 into thecylindrical fibrous body 60.

The principal or a supplemental amount of the binder component either ina liquid vehicle or as dry particles may be introduced into the mass offibers Wrapped about the `mandrel by the apparatus of FIGURE 9.

When the fibrous product is divided into short units for filter cores, agreater surface for exposure to the fluid to be cleaned by being movedradially through the wall of the core may be secured through shapingchannels in the outer surface.

This may be accomplished, as demonstrated in FIG- URES and 11, byforming helical grooves 95 by saws or cutters in the cylindrical body asit passes in the helical path over the end of the mandrel. The body isthus supported against the cutting force by the mandrel 13. To provideoperating space for the saws yand still have closely arranged grooves95, two saws 91 and 92 may be positioned on one side of fibrous body andtwo saws 93 and 94 placed on the opposite side.

For most products for which the tubular bodies are intended uniformstrength, thickness and density throughout the bonded fibrous glassbodies is desirable. However, from the standpoint of economy and tosecure special properties in the fibrous bodies, it is advantageous insome instances to so fabricate the tubular structure that it has areasof extra strength and density sufficient to maintain the product in astabilized form and utility in spite of intermediate regions of sparsecontent and comparative weakness. Such regions not only effect a savingsin material but also provide a flexibility Iof benefit in any bendingrequired in the installation and use of the product.

An example of a tubuar body having such non-uniformity is one in whichthere is a helical region of extra density and strength. A body of thistype may be fabricated by having the belt 23 directed around the mandrelin la helical path with an eight inch lead in each turn and delivering apack of fibrous glass in a width of ten inches so that an edge thereofproceeds evenly under the belt and the pack follows the same helicalpath as the belt. With this arrangement each turn around the mandrel ofthe pack will overlap the preceding turn only two inches. While thecompressing action of the belt 23 and the ironer 48 may establish auniform thickness in the wall of the tubular body, there will be in thearea of the overlap a narrow continuous, helical strip of double densityand strength.

As shown in FIGURE 7, the turn ofthe pack around the mandrel isoverlapped by the subsequent turn 81 creating the densified strip or rib83. The width of this stabilizing -rib may be selectively controlledwithin a wide range by variationof the overlap of the helical path.Additional strength may be provided in this helical strip area byinserting under the leading edge of the pack as it moves under .the beltstrands or strips of fibrous glass, metal, paper, plastic or byintroducing settable materials in fluid form into that portion of thepack. In producing a tubular body having a densified helical ribcontaining two layers of the fibrous pack, the overlap of each turn ofthe fibrous pack over `the preceding turn around the mandrel must beless than one half the width of the pack. Accordingly, the lead betweenadjacent turns of the pack around the mandrel should have a dimension ina range between slightly more than half the width of the pack andslightly less than the `full width of the pack.

The tubular products of this invention in most cases serve asconventional air ducts or pipe insulation. With an impregnation of clayor other inert material they are capable of utility in a hightemperature environment. With a smooth liner such as provided byv-aneoprene film deposed upon the under surface of the pack as delivered tothe forming apparatus, the tubular product is particularly adapted forcarrying air flow at high velocity. For underground installation theproduct is waterproofed by an impervious cover of plastic film or othersealing material. In shorter sections the cylindrical form of bondedfibrous -glass is useful as insulating liners of containers, as `dunnagefor shipment, and filter cores.

While for purposes of illustration, specific designs, dimensions andcompositions have been referred to herein, it should be understood thatquite a broad range of specifications are adaptable to the products,apparatus and processes of this invention and that there are numerousother modifications available within the scope of this invention and theappended claims.

We claim:

1. A method of producing a tubular insulating body of fibrous glasswhich comprises directing a flat belt helically around a mandrel,directing a generally planar, compressible, porous pack .of fibrousglass impregnated with a heat curable binder in a path tangential of themandrel Iand adjacent to the belt whereby the pack is gripped andcompressed between the belt and the mandrel and is pulled by. the beltin a helical path around the mandrel, and the porous tubular body formedby the helical turns of the pack is advanced along the mandrel by thebelt, and directing binder curing hot air under pressure outwardly froma longitudinal section of the mandrel through the tubular body anddirecting additional binder curing hot air from an exterior sourceinwardly into the porous tubular body supplementing the curing action ofthe hot air directed outwardly from the mandrel.

2. A method of producinga tubular insulating body of fibrous glass whichcomprises directing a iiat, belt helically around a mandrel, directing agenerally planar, compressible, porous packV of iibrousglass impregnatedwith a heat curable jbinder in a path tangential of the mandrel andadjacent to the belt whereby the pack is gripped and compressed betweenthe belt and the mandrel and is pulled by the ybelt in a helical patharound the mandrel, and the porous tubular body.I formed by the helicalturns of the pack is advanced along the mandrel by the belt, anddirecting binder curing hot air under pressure outwardly from alongitudinal section of the mandrel through the tubular body anddirecting additional binder curing hot air at a higher pressure from anexterior source inwardly through the porous t-ubular body in overcomingopposition to a portion only of the hot air directed outwardly from themandrel.

3. A method of producing a tubular insulating body of brous glass whichcomprises directing a at belt helically around a mandrel and directing agenerally planar, compressible pack of brous glass impregnated with aheat curable binder in a path tangential of the mandrel and adjacent tothe belt as the belt approaches and starts to turn around the mandrelwhereby the pack is gripped and compressed Abetween the belt and themandrel and is pulled by the belt in a helical path around the mandrel,and the tubular body formed bythe helical turns of the pack is advancedalong the mandrel by the belt, the lead of the helical path of the packaround the mandrel being in a range lying between slightly more thanhalf the width of the pack and slightly less than the full width of thepack whereby the tubular body has alternate helical areas of single anddouble layers of the pack due to the overlapping of each turn of thefibrous pack over less than one-half of the Width of the preceding turnthereof around the mandrel.

4. A methodof producing a tubular insulating body of iibrous glass whichcomprises directing a` flat belt helically around a mand-rel anddirecting a generally planar compressible porous pack of brous glassimpregnated with aheat curable binder in a path tangential of themandrel and adjacent to the belt as the belt approaches and .starts to.turn around the mandrel whereby the pack is gripped and compressedbetween the belt. and the mandrel andis pulled by the belt in a helicalpath around the mandrel, and the porous tubular body formed -by thehelical turns of thepacked is advanced along the mandrel by the belt,and forcing impregnating material into the porous tubular body as it isadvanced along the mandrel. y r l 5. A method of producing a tubularinsulating body of fibrous glass whichcomprises directing `a flat belthelically` around a mandrel and -directing a generally planarcompressible pack of -iibrous glass impregnated with a heat curablebinder in a path tangential ofuthe mandrel and adjacent to the beltwhereby the pac-k is gripped and compressedbetween the belt and themandrel and is pulled by the belt in a helical path around the mandrel,and the tubular body formed by the helical turnsof the pack is advancedalong vthe mandrel by the belt, and cutting a helical groove in theouter surface of the tubular body as the body is advanced along themandrel.

References Cited UNITED STATES PATENTS A. R. NOE, Primary Examiner.

R. KUCIA, Assistant Examiner.

1. A METHOD OF PRODUCING A TUBULAR INSULATING BODY OF FIBROUS GLASS WHICH COMPRISES DIRECTING A FLAT BELT HELICALLY AROUND A MANDREL, DIRECTING A GENERALLY PLANAR, COMPRESSIBLE, POROUS PACK OF FIBROUS GLASS IMPREGNATED WITH A HEAT CURABLE BINDER IN A PATH TANGETIAL OF THE MANDREL AND ADJACENT TO THE BELT WHEREBY TTHE PACK IS GRIPPED AND COMPRESSED BETWEEN THE BELT AND THE MANDREL AND IS PULLED BY THE BELT IN A HELICAL PATH AROUNG THE MANDREL, AND THE POROUS TUBULAR BODY FORMED BY THE HELICAL TURNS OF THE PACK IS ADVANCED ALONG THE MANDREL BY THE BELT, AND DIRECTING BINDER CURING HOT AIR UNDER PRESSURE OUTWARDLY FROM LONGITUDINAL SECTION THROUGH THE TUBULAR BODY AND DIRECTING ADDITIONAL BINDER CURING HOT AIR FROM AN EXTERIOR SOURCE INWARDLY INTO THE POROUS TUBULAR BODY SUPPLEMENT THE CURING ACTION OF THE HOT AIR DIRECTED OUTWARDLY FROM THE MANDREL. 